Anybody try swapping an old-school manual transfer case (# NPxxx?) for a NVG149 AWD t-case for dyno work? My Tuner wants to do my high boost 12-18lbs on his dyno but I have an AWD NVG149 on the back of my 4L80E. I'm hoping I can pick up a used/cheap manual t-case that will bolt to a 4L80E, manually lock it in 2WD and then get a driveshaft cut to fit for the rear. I know some people have just pulled their front driveshaft at the Dyno and went for it but my Tuner thinks it's asking for trouble.

Sugestions? Correct t-case I should be looking for?

Rick

 

I'm looking for simular solution. My front diff is noisey on a 2001 Denali awd.

I found this, it looks like the front diff would need the internals changed in order to disengage the front axle. Also the transfer case has a differential unit of sorts built into it. So power will be sent to least resistance, which, if you removed the front drive shaft, it would be very hard on things

https://www.performancetrucks.net/fo...-457402/page2/

either way I'm just tuning in to see what answers come up here. hummmmm

 

Are you not going to run the front drive shaft, it may work but that is ALOT of work just to get it on the dyno. Plus the #'s will be higher dut to you not turning the front diff.

 

tansfer case exploded view

Service Information

Looks like I'm SOL, and that's why Rick needs a regular 4x4 case

 

If the viscous coupling is in the "hump" mode too long, severe damage will occur. To prevent damage to the viscous coupling, DO NOT:

Tow with only two wheels down
Drive without one propshaft
Drive with a "donut" spare tire for an extended period of time


from this site

DenaliTrucks Document Index

under "detailed transfercase info"

 

You will also need to get the different input gear for your spare case since theyre different between the awd and 4wd case. Why must it be done on the dyno? Plenty of very fast guys have never had their trucks on the dyno period much less for tuning...

 

Just looking at all my options. I can usually find transfer cases pretty cheap.
If it ended up being a simple TC swap, I wouldn't bother with the front DS.

That sounds like a good thing.

I bet the numbers would be within 1-2%.

I converted my NVG149 to a 32 spline input so I could run the heavier 4L80E output shaft. I used one of EAD's modified units.

Rick over at Synergy is doing the tune and has no problem doing the "low boost" 12lb tuning on the road. He said he would rather do the "high boost" 18lb tune on the dyno to run it under a full load the entire RPM range and dial in every cell.

I also have to admit I'd like to see what kind of #'s it can hit. I'll be taking it to the track soon to get my true measure of performance.

I actually picked up a spare NVG149 yesterday as a little "insurance" if something goes wrong so we will drop the front DS and do the dyno runs. I've talked to a few of our more "experienced" members and feel pretty confortable giving it a try. They've collectively done it a dozen+ times. It sounds like the trick is to not move the truck after it's dropped, coast down from the pull without hitting the brakes and put it back in park as soon as the rear wheels stop turning.

Rick

 

Where did you find a 149 case? I've been looking all over for a deal on one.

 

On Craigslist. Looking for a manual transfer case and ran into it.

Rick

 

Lucky!

If you don't mind, how much was it?